Processes for retaining water in concrete for the hydration of cement



June 24, 1930. c. MCKr-:ssoN 1,768,356

PROCESS FOR RETAINING WATER TN CONCRETE FOR THE HYDRATION OF CEMENT Filed July 2, 1928 rt A F/c. Z.

INVENTOR.

l MWW/ Patented June 24, 1930 UNITED STATES PATENT OFFICE CLAUDE L. MCKESSON, OF SACRAMENTO, CALIFORNIA, ASSIGNOR TO AMERICAN BI- TUMULS COMPANY, E SAN FRANCISCO, CALIFORNIA, A CORPORATION OF DELA- WARE PROCESSES FOR RETAINING TXATER IN CONCRETE FOR `'.IEIIIEI HYDRATION OF CEMENT Application filed July 2, 1928. Serial No. 289,844.

The object of my invention is to provide simple, efficient and inexpensive means for retaining in concrete sufficient of the mixing water during the period following the placing thereof to insure theproper hydration of the cement and the development of the required tensile and compressive'strengths. vThis beneficial result is accomplished without permanently discoloring the concrete.

Incidental to the conservation of water dur-y ing the curing period and without additional expense it also provides means by which markings may be produced on the surface concrete pavement and bridges for traffic direction or other purposes.

The process and means by which these and other beneficial results are obtained are described herein and are shown in the accompanying drawings in which Fig. 1 shows one method of placing a covering of paper, felt, fabric or similar vmaterial on a freshly finished concrete pavement.

Fig. 2 shows a fragmental cross section of pavement with completed protective covering in place. This section is taken on the dotted line A. A. in Fig. 1.

Throughout the views like characters refer to the like elements. A

In the drawings 1 indicates a body of freshly placed concrete. .2 refers to alayer of, granular mineral paper, felt, or other covering material which is placed directly upon the surface of the concrete such materials being generally absorbent or of waterpervious nature. 3 indicates a second layer of paper, felt, fibrous or -fabric covering material which is sometimes superimposed upon material 2. 4 is a surface coating of waterproofing material such as tar, asphalt, or petroleum residuum preparation, which is spread over the cover material. space between the edges of parallel strips of the coverings 2 and 3 which permits vthe Waterproofing material spread over the surface'to come into contact with the surface of the concrete between the parallel strips to which it adheres and remains after the removal of the coated cover materials 2 and 3, forming thereby a traffic guide line :upon

the light colored natural surface of the concrete.

The method of applicationof the treatment is briefiy described as follows:

The 'material 2 is first spread upon the freshly placed concrete. The cover material 2 may consist of sand or similar granular mineral matter. In such case only the f one layer is needed. When paper, felt, or other pliable material is used it is sometimes desirable to place it in two successive layers on the concrete. This method is illustrated in Fig. 1 and the first layer is designated as 2, the second layer .as 3. The placing of pliable material vis conveniently accomplished by having the cover material in rolls, as shown in Fig. l, so placed that successive and interlapping layers may be placed following the finishing of theconcrete. The presence of this covering has the immediate effect of protecting the surface of concrete 4 from wind, sun, or injury from showers.l The next stage which usually follows withina period of from a few minutes to several hours consists of the'application on the said covering'already placed of a thin layer or film of waterproof material such as asphalt, petroleum residue, tar, varnish, or lacquer. Asphalts, cut back or emulsified asphalt, are generally most economical and preferably the latter is used because, already containing water it has a natural affinity for the covering which is, by the time of its application, damp concrete.

Under unusual conditions the placing of the bituminous layer 5 may be deferred for a period during which the coverings 2-and` 3" are kept wet by sprinkling with water. In this way additional water may be supplied to aid in hydration.

If the cover is allowed to remain a considerable period before waterproofing without sprinkling with water it will tend, by evaporation, to reduce the water content in the surface of the concrete, a desirable accomplishment with very wet concrete.

After the hydration of cement in the concrete has progressed to the desired point the coverings 2 and 3 are removed from the with moisture from the wet tard passage of pavement taking with them the waterproof coating 4. This leaves the concrete clean and free from discoloration exceptwhere, as stated, an opening 5 has been left between parallel strips of cover material to permit the waterproong material to reach the concrete to which it adheres and produces the guide line, as stated.

The exact thickness `or kind of material used in coverings 2 and 3 is not essential to this invention. Usually very thin inexpensive paper meets the requirements. The number of layers may be varied to meet the conditions prevailing on the work. A single Vlayer 2 coatedwith a waterproof coating 4 is somewhat more difiicult to remove; otherwise, it satisfactorily accomplishes the purose. p-Grranular material such as sand or earthy matter ordinarily available adjacent to highway construction also affords an economical and satisfactory cover material. In such case the covermaterial may be spread on the wet concrete to any desired thickness and covered with bituminous emulsion or other liquid asphaltic material with or without prior application of additional water. ln due time after the curing of the concrete has been effected the cover material with its asphaltic coating may swept to the sides of may be compacted to provide shoulders wherein the binding qualities of the disintegrated asphalt may be utilized.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is: y

y1. The'process of retaining water in concrete for hydration of cement by. placing water-` ervious cover material on the. surface o the concrete and byapplying to said cover material a treatment of nonabsorptive material. f

2. The process of retaining water in con- 'crete for hydration of cement by covering the concrete with material which will not permanently adhere to the concrete and by treating said material with a coating of material of a waterproofing nature adapted to resist the passage of waterv or water vapor from the concrete. Y

3. The process of retaining water in concrete for hydration of cement by placing a removable protective coveringl on the concrete and by coating said rprotective coveringwith waterproofing material adapted to remoisture through the said protective coating. g

4. The process of retaining water in concrete for hydration of cement by covering the concrete with a porous material and by applying to said porous material a surface treatment of waterproofing adapted to prevent evaporation through said porous material of water contained in the concrete.

be disintegrated and the roadway where it terial adapted to come into close contact .with the surface of said concrete and by dis tributing von the uppermost of said cover material a coating of liquefied bituminous material.

6. The process of retaining water inconcrete for hydration of cement by placing thereon cover material, said cover material being 'so placed as to leave the bare surface of the concrete between the edges thereof at predetermined intervals for the purpose of forming trafiic markings and a liquid water-A proofing treatment applied to the surface of the said cover material and to the exposed concrete between the edges of the cover material, adapted to retard the escape of moisture from the concrete.

7. The process of lretaining water in concrete for. hydration of cement by covering said concrete with removable cover material and by coating the said cover material with tially as described and for the uses and purposes set forth. v

8. A'process'of curinghydraulic cement concrete which comprises covering the concrete while still wet with absorbent material, applying water to said absorbent material, applying waterproofing material "to the surface of said absorbent material to retard the loss of water during the curing period and removing said absorbent material and waterproofing material from the cured concrete.

9. A process ofcuring hydraulic cement concrete which includes applying a layer of water-pervious material while the concrete 1s still wet, applying bituminous emulsion to substantially seal lthe surface of the, water-pervious material during the curing period and removing the waterfpervious material and sealing material from the cured concrete. v p

CLAUDE L. MQKESSON.` 

